Bis-glycolic acid amides of 2, 6-diamino-pyridines and method of preparing them



Patented Feb. 8, 1949 smrss PATENT BIS-GLYCOLIC. ACID AlHIDESOF 2,6-Dll- A'MINO' PYRIDINES AND METHOD OF PREPARING THEM William A; Iiott,.Maplewood, and; Jacki Bernstein and Barbara Stearns, New Brunswick, N. L, assignors to E. lie-Squibb 81:80:15,. New York, N..Y., a. corporation. of New York No'Drawing. Application July 31 1943, I S'El'iEI NO. 496,944

6 Claims. 1 This invention relates to, and hasfor'its object the'provision of: (A) oxy-carboxylic acid amides of diamino-pyridines; (B) acid-addition salts thereof; and (C) methods of' preparing (A) and (3). Certain of compounds (A) and (B) are valuable chemotherapeutic agents, being especially promising as antimalarials.

The invention comprises especially compounds of'thegeneralFormul-ae I and: II.

wherein R represents alkylene or arylene, vR represents hydrogen, alkyl or alkoxy;v and X represents hydrogen; aIkyLaryl or acyl.

The oXy-carb'oxylic' acid amides of diaminopyridinesmay be obtained by reacting the corresponding. diamino-pyridine with the correspond.- ing oxy-carboxylic acid, or a lower alkyl ester or (acid) halide thereof, under amide-forming conditions. Thus, these compounds may be 010- 1 tained by reacting a diamino-pyridine with an acyloxy-carboxylic acid halide in a suitable solvent, especially dioxane, or by fusing a dlamino-pyridine with the oxy carboxylic acid per so. By suitable variation of the proportions of the reactants, one can obtain eithera monoamide (I) or bisamide (II). Alternatively, the mono-amides (I) may be obtained by reacting the corresponding halo-amino-pyridi-ne with the corresponding oxy-carboxylic acid-or a lower, alkyl ester or (acid) halide thereof-and replacing the lialo group with an amino group.

The oxy-carboxylic acid amides of diaminopyridines may be converted into acid-addition salts with hydrochloric, sulfuric, and other. acids commonly used to solubilize aminebases.

The following examples are illustrative. of the invention:

Example 1 Aisolution of 60 g. acetyl-salicylyl chloride in 156 cc- .dioxane. is added dropwiseto a cooled solution of 66 g. 2,6-diamino-pyridine in 500- cc. dioxane-, and the reaction mixture is stirred for an additional hour. The precipitate. which forms is filtered. off and discarded. The filtrate is.con-- centrated. under reduced pressure until the dioxane is removed; and the: residue, an oil, is dissolved in 500 cc. normal hydrochloric acid and reprecipitated by adding an equivalent amount of dilute sodium hydroxide-.. Theprecipitate thus obtained isrecrystallizedfrom a mixture oiuben Zene and absolute alcohol. The: product, 2- amino-G-salicylanddo-pyridine, isa white: solid. melting zit-1 78 4.79 0..

Example 2 (a) A solution of 55.3 g. acetyl-mandelyl chloride in 50 cc. dioxaneis'added over a period of 15' minutes, while stirring: and maintaining the: temperature below 30 to a. solution-oi. 69-.2 g'. Zfi-diaminmpyridine in. 3-50 'ec..dioxane-. The stirring. is continued for'an. hour; and. the: precipitated 2,6-dia1nino-pyridine monohydro-- chloride is" filtered: off. The filtrate concentra-ted until nomore; dioxanedistills; off; and. the residueis extractedwithether, andthe ether extract is concentrated on. thesteam bath. The residue, Z-aminoa-G- (acetyl-mandelamido); -pyri:- dineyis a sticky substance at room temperature;

(17) The product is converted to its; hydrodried-invacuum, and recrystallized from alcohol";

Example 3 27.8g. 2,6-di-amino-pyridine and 42 g. glycolic acid are fused together at;1-20: C. under vacuum:,.

until the mass solidifies. Water is then. added, and the insoluble product 2,6-bis(glycolamido )s-- pyridine, is filteredoff and recrystallizedirom water. It is: a. whitecrystalline materialrmelting between 210 and 215 C. (depending on the rate at whichthe-melting point. is taken) I Exmnpl'e. 4. I ('a') '80 g. 4-methyl-pyridine is' mixedwith I60 gt dimethylan-ili-ne and' I44- gi s'odamideQandi-hatd 3 about 10 hours at 130-150 0., followed by about 6 hours at 170-200" C. at the end of which time the hydrogen evolution is usually complete. The mixture is then cooled; the dimethyl aniline is decanted oil, and the residual solid is decomposed with water, a mixture of solid and alkaline solution being obtained. This solution is extracted with isopropanol; and the isopropanol solution is dried, and then concentrated under reduced pressure to remove all solvent. The residual dark syrup thus obtained is treated with chloroform until only a small amount of tar remains undissolved, and filtered; and the filtrate is concentrated and cooled. From this solution 2,6- diamino-l-methyl pyridine separates out in crystalline form. After recrystallization from ether it melts at 100 C.

b( 12.3 g. 2,6-diamino-4-methyl pyridine and 15.2 g. glycolic acid are fused together at 120 C. under vacuum, until the mass solidifies. Water is added; and the insoluble product, 2,6-bis(glycolamidm-d-methyl pyridine, is filtered off and recrystallized from 50% alcohol.

Example 5 By substituting the same quantity of 3-methylpyridine for the 4-methyl-pyridine in the procedure of Example 4 .(a), the compound 2,6-

diamino-3-methyl-pyridine is. obtained; and byreacting this compound with glycolic acid as described in Example 4(2)), 2,6-bis(glycolamido) 3-methyl-pyridine is obtained.

Example 6 (a) 12.3 g. 3- methoxy-pyridine is dissolved in 40 cc. concentrated sulfuric acid at C., and cc. fuming nitric acid ((1. 1.6) is added with vigorous stirring and cooling. An additional 40 cc. concentrated sulfuric acid is then added, and the reaction mixture is heated for six hours on a steam bath. Th solution, after cooling, is poured into 500g. crushed ice and water; and the pre-' cipitate, 2,6-dinitro-3-methoxy-pyridine, is filtered off, washed with water, sodium bicarbonate solution, and water, and then dried. On recrystallization from absolute alcohol, it melts at 113- 1.99 g. 2,6-dinitro-3-methoxy-pyridine is dissolved in '70 cc. glacial acetic acid and 30 cc. acetic anhydride, 0.1 g. platinum oxide catalyst is added, and the reaction mixture is shaken with hydrogen at atmospheric pressure, until the theoretical amount of hydrogen is absorbed (four hours). The reaction mixture is then filtered, and the acetic anhydride and acetic acid distilled ofi under reduced pressure. The residue is poured into 100 g. ice and water, which is then saturated with potassium carbonate; and the precipitate, 2,6- diacetylamino-3-methoxy-pyridine, is filtered off. On purification by recrystallizing the crude material from water, and then from a mixture of benzene and chloroform, it melts at 1735-1745 C.

2 g. 2,6-diacetylamino-3-methoxy-pyridine is boiled with 50 cc. one-normal sodium hydroxide solution (in the presence of hydrogen sulfide) for one hour; and the cooled solution is neutralized with acetic acid, and evaporated to dryness under reduced pressure. The residue, crude 2,6-diamino-3-methoxy-pyridine, is recrystallized from benzene.

Alternatively, the 2,6-diacetylamino-3-methoxy-pyridine (2 g.) is boiled with 20 cc. of 10% hydrochloric acid (saturated with hydrogen sulfide) for a half hour; and the reaction mixture is cooledan'd. evaporated to drynessunder re-' added, and the insoluble product, 2,6-bis(glycolamido) -3-methoxy-pyridine, is filtered off, and recrystallized from 50% alcohol.

Example 7 (a) 17.3 g. 2-bromo-6-aminopyridine and 7.6

g. glycolic acid are fused at C. for 15 hours under reduced pressure; and the solid mass, 2+

bromo-G-glycolamido-pyridine, is ground with water, filtered and recrystallized from absolute alcohol. 1

(b) 11.6 g. 2-bromo-G-glycolamido-pyridine is heated with 50 cc. aqueous ammonia (d. 0.90) for 20 hours at -200 C. in a sealed tube; and the resulting solution is concentrated to 25 cc., treated with activated charcoal, filtered and cooled. On standing, crystals of 2-amino-6-glycolamidopyridine are formed; and the product is recrystallized from 50% alcohol.

Manifestly, a large number and variety of other oxycarboxylic acid amides of diamino-pyridines and acid-addition salts thereof may be obtained by the procedure of the foregoing examples, using the appropriate reactants. The following additional compounds, inter alia, are thus obtainable:

2-amino-6-lactamido-pyridine 2,6-bis(1actamido) pyridine 2-amino6- (a-hydroxy-butyramido) pyridine 2,6-bis (ethoxy-acetamido) -pyridine Among other reactants utilizable in the procedure of the foregoing examples for the preparation of the compounds of this invention are:

Oxy-carbozr'Jlic acid reactants Phenoxy-acetic acid chloride Lactic acid a-Hydroxy-butyric acid a-Hydroxy-caproic acid e-Hydroxywaleric acid Acetonic acid Saccharic acid Ascorbic acid p-AcetoXy-phenylacetyl chloride Diamz'no-pyrldine reactants 2,6-diamino-3-nitro-pyridine 2,6 -diamino-3,5-diethoxy-pyridine 2,6-diamino-4-bromo-pyridine 2,3-diamino-pyridine 2,5-diamino-pyridine 3,4-diamino-pyridine 3,5-diamino-pyridine The invention is not to be construed as in any sense. restricted to the foregoing specific examples, compounds, reactants, or procedures, but may be variously otherwise embodied within the scope of the appended claims.

We claim: 1. A compound of the general formula xoomooNn NHCOCHzOX wherein R represents a member of the group consisting of hydrogen, alkyl, and alkoxy, and X represents a, member of the group consisting of hydrogen, alkyl, aryl and acyl radicals.

2. A compound of the general formula.

XOOHzOONH NHCOOHZOX wherein R represents amember of the group consisting of hydrogen, alkyl, and alkoxy, and X represents a member of the group consisting of hydrogen, alkyl, aryl, and acyl radicals, which comprises fusing under vacuum glycolic acid and a compound of the general formula wherein R has the meaning given hereinbefore.

WILLIAM A. LOTT. JACK BERNSTEIN. BARBARA STEARNS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,830,301 Tiza, Nov. 3, 1931 1,979,351 Schneiderwirth Nov. 6, 1934 2,043,547 Krassny June 9, 1936 2,080,517 'I'isza May 18, 1937 2,187,847 Andersag Jan. 23, 1940 2,262,357 De Groote Nov. 11, 1941 OTHER REFERENCES Chem. Abstracts, vol. 33, p. 8923 (1939) 

